VARIABILITY IN THE SACCHARIDE, PROTEIN, PHENOLIC-ACID AND SAPONIN CONTENTS OF 4 MARKET CLASSES OF EDIBLE DRY BEANS

The content and composition of the saccharides, protein and amino acids, phenolic acids, and saponins of four market classes (navy, dark red kidney, pinto and Black Turtle Soup) of edible dry beans (Phaseolus vulgaris L) were determined. These compounds are potential precursors of flavour development in the processed beans and may contribute to the unique flavour characteristics of the various bean classes. The contents of sucrose and stachyose were significantly different (P < 0.05) for the four bean classes and ranged from 2.63 to 4.80 g per 100 g and 2–81 to 4–21 g per 100 g, respectively. Total nitrogen contents ranged from 3–92 to 4–71 g N per 100 g and were significantly different. The distribution of the amino acids was similar for the four bean classes. Coumaric, ferulic, sinapic and cinnamic acids were identified. The phenolic acid soluble esters were the predominant fraction, with lesser amounts of the free and insoluble phenolic acids. The total saponin contents of the bean classes were similar. Significant (P <0–05) differences in the distribution between the three major saponin components were observed. Copyright © 1990 John Wiley & Sons, Ltd